FIG. 1 is a schematic view of a typical 3D display device. Referring to FIG. 1, the 3D display device 100 includes an LC display panel 110 and an LC lens device 120. The LC lens device 120 includes an LC lens array 130 and a driving device 140. Viewing a display surface of the LC lens array 130 along a direction X, it is can be seen that the LC lens array 130 includes a plurality of LC lenses arranged in parallel, as shown in FIG. 2. FIG. 2 is a top view of the LC lens array 130 along the direction X of FIG. 1, and numeral 132 represents an LC lens.
The 3D display device 100 can operate respectively in a two-dimensional (2D) display mode and a 3D display mode. FIG. 3 is a schematic cross-sectional view of each LC lens 132 in the 2D display mode. Referring to FIG. 3, each LC lens 132 includes an upper substrate 132-1, an upper electrode 132-2, an LC layer 132-3, a plurality of lower electrodes 132-4, and a lower substrate 132-5. Each of the lower electrodes 132-4 is electrically connected the driving device 140 to receive driving voltages provided by the driving device 140. In the 2D display mode, each of the lower electrodes 132-4 of the LC lens 132 is not supplied with the driving voltages, and accordingly LC molecules of the LC layer 132-3 are arranged in parallel to the upper electrode 132-2. Thus lights passed through the LC layer 132-3 have no refractive index difference, and the 3D display device 100 can operate in the 2D display mode.
FIG. 4 is a schematic cross-sectional view of each LC lens 132 in the 3D display mode. Referring to FIG. 4, the same numeral as that in FIG. 3 represents the same component as that in FIG. 3. In additional, labels V1-V4 shown in FIG. 4 respectively represent the driving voltage supplied to corresponding lower electrode 132-4. Due to values of the driving voltages V1-V4 being from the maximum to the minimum according to an order from the driving voltage V1 to the driving voltage V4, that is, the driving voltage V1 is the maximum and supplied to the right-side lower electrode 132-4 and the left-side lower electrode 132-4, and the driving voltage V4 is the minimum and supplied to the middle lower electrode 132-4, the LC molecules of the LC layer 132-3 are arranged shown as in FIG. 4, and accordingly the refractive index difference of the lights passed through the LC layer 132-3 shows a lens-like distribution. Therefore the LC lenses 132 can make the 3D display device 100 operating in the 3D display mode.
Due to a cell gap of the LC layer 132-3 of each LC lens 132 producing great effects on brightness, contrast ratio and response time of the 3D display device 100, some designs and driving methods are developed to make the refractive index difference of the lights passed through the LC layer shows a Fresnel lens-like distribution, for example, the cell gap of the LC layer is decreased to increase the brightness and the contrast ratio of the 3D display device and decrease the response time of the LC molecules. However, due to many ball spacers usually disposed between the upper substrate and the lower substrate to maintain the cell gap of the two substrates, when all the lower electrodes of each LC lens are supplied with the driving voltages in the 3D display mode, the LC molecules adjacent to the ball spacers are arranged towards unexpected directions, shown as in FIG. 5.
FIG. 5 shows one case of the LC molecules arranged towards the unexpected directions. Referring to FIG. 5, the LC lens 500 operates in the 3D display mode, and the refractive index difference of the lights passed through the LC layer of the LC lens 500 shows a Fresnel lens-like distribution (labeled as 502). However, duo to the LC molecules 506 in a region 504 effected by the adjacent ball spacers (not shown), the LC molecules 506 is not tilted towards an ideal direction (in an ideal design of a Fresnel lens, all the LC molecules are tilted towards a center of a main lobe region of the Fresnel lens, that is, a center of the Fresnel lens), but is tilted towards edges of the Fresnel lens. Therefore, when the LC lens array employing the LC lenses 500 are used to display a 3D image, discontinuity lines of the edges of some LC lenses 500 in the 3D image will shift, and result in more new discontinuity lines being produced, that is, so-called dotted Mura is produced, shown as in FIG. 6.
FIG. 6 shows one case of the Mura. Referring to FIG. 6, numeral 602 represents a ball spacer, and numeral 604 represents a discontinuity line. Shown as in FIG. 6, the discontinuity line 604 is anomalous due to the ball spacer 602, and cannot show a linear distribution like other parallel discontinuity lines.